Field of the Invention
The invention lies in the field of wheels made out of fiber reinforced material for passenger vehicles such as cars, motorcycles, etc.
Discussion of Related Art
Polymeric composite materials became popular around 1970. As their name denotes composite materials are a compound of fibrous material which provide mechanical capacity and a surrounding matrix material in which the fibers are embedded and which is responsible for bonding, support and protection of the fibers. The mechanical capacity can be significantly increased in that the fibers are oriented in the direction of the occurring load. Depending on the field of application, carbon fibers, glass fibers or Kevlar® fibers or a mixture thereof is commonly used. The fibers are processed either in dry or impregnated form. One advantage of composite material is the low specific weight compared to metal alloys. Wheels made out of composite material offer significant weight saving compared to similar wheels made out cast aluminum or steel. A further advantage is the higher design flexibility compared to wheels made out of metal. In addition, less energy is necessary for the process of making the wheel.
U.S. Pat. No. 3,369,843 published on 20 Feb. 1968 is directed to a laminated vehicle wheel. The wheel comprises a relatively flat, axle-receiving hub section and an outer laterally extending rim. The hub and the outer rim sections are integrally formed of a plurality of radially extending triangular plies of reinforced synthetic resin material diverging outwardly from said hub section in circumferentially overlapping relation to one another.
GB 1 372357 published on 30 Jan. 1974 describes a vehicle road wheel, which comprises a body and rim formed from a cellular rigid plastics core enveloped in a skin of plastics material. A reinforcing element, e.g. a steel disc, may be embedded at least partly in the body, the element being secured to the core by mechanical locking (e.g. by the provision of holes forming a key for the core material) or by bonding, or being bonded on one surface to the skin. The core may be made of injection moldable material (e.g. an ABS copolymer, a polyurethane, a nylon, a polyethylene, or polypropylene), or castable material (e.g. a polyurethane, an unsaturated polyester or an epoxy resin). The skin may be made of injection moldable material (e.g. an acetal polyamide, a polyphenylene oxide, a polycarbonate, a polysulphone, a polyurethane, or polypropylene), which may be fiber reinforced, or may be formed from a material suitable for skin production using lay-up techniques, e.g. a fiber reinforced polyester or epoxy resin, the fibers in the skin material being glass, carbon, boron, asbestos or metal.
U.S. Pat. No. 5,277,479A published on 11 Jan. 1994 describes a resin wheel of a one piece type. The wheel comprises a rim and a disk molded integrally. A portion between an axle hole of the disk and the rim is in a form of a blind plate with no holes excepting for bolt holes. The wheel is formed by injection molding or injection compression molding of a fiber reinforced thermoplastic resin.
U.S. Pat. No. 4,900,097A published on 23 Aug. 1988 describes a car wheel made of engineering polymer material. The wheel is connected to a disc provided with holes for the fixing components. Between the wheel disc and the car hub, a heat insulating plate is inserted. In the zone of each hole for the fixing components a plurality of axially, uniformly arranged pins are present, the faces of which are in contact with supporting plates, disposed on both sides of the disc. The coefficient of linear expansion of the pins is equal to that of the fixing components.
U.S. Pat. No. 4,072,358A published on 7 Feb. 1978 describes a compression molded cut-fiber reinforced plastic wheel for pneumatic tires. A polyimide plastic containing about 65 percent by weight of cut glass fiber is compression molded.
U.S. Pat. No. 3,917,352A published on 4 Nov. 1975 describes a wheel having a fiber reinforced plastic central hub portion. A rim is formed to the hub portion for receiving a tire. The rim comprises first and second circumferential, tire engaging bead regions on opposite sides of the rim. The rim comprising a plurality of resin encased filament lengths extending continuously from one bead region over the hub portion to the opposite bead region.
U.S. Pat. No. 3,811,737A published on 21 May 1974 describes a wheel of reinforced resin, which comprises a disc formed with a plurality of fastening holes. Plates of rigid material are embedded in the disc and formed with bores aligned with the fastening holes. The plates have an outer face that extends out at least as far as the immediately surrounding portions of the outer face of the disc.
WO 06097856 published on 21 Sep. 2006 concerns a vehicle wheel comprising a rim for receiving a tire and a spoke unit or a wheel disc connecting the rim to the hub. The rim is made of plastic material and the spoke unit or the wheel disc of metal. The rim is connected to the spoke unit or wheel disc by form-closure and/or by force-closure of the material. The invention aims at enabling the wheel disc to be accurately positioned relative to the rim base and at providing a wheel with an attractive design. Therefore, the spoke unit, or the wheel disc are connected via at least one connecting element guided through the rim base and the connecting element is housed in the spoke unit or the wheel disc so as to be completely covered by a tire or by the spoke unit or the wheel disc.
WO 94226A published on 13 Oct. 1994 shows a method of how to build wheels out of metal with varying designs using the same basic wheel structure in combination with individual metal cover elements. The shown cover elements only cover the wheels' hub and spoke structure of the basic wheel structure and do not fully extend to the peripheral rim of the wheel. Hence the design of the peripheral rim is not affected by the cover elements.
WO 11 000070A published on 6 Jan. 2011 shows a wheel made out of a polymeric composite material comprising a homogeneous mixture of a thermoplastic matrix and synthetic fibers, made in a single piece by an injection process. The document further describes the use of different types of metallic inserts in the wheel's central region in order to reinforce the connection of the wheel to a vehicle.
U.S. Pat. No. 7,296,860B published on 20 Nov. 2007 shows a protective ring which is fitted around the periphery of a rim. The aim of the invention is to protect light alloy wheels against damage on their side surfaces and to enhance the appearance of the rim. The protector therefore is impact-absorbing and can be built-up using multiple layers. The ring can be replaced after reaching a certain degree of damage, which can be indicated using a damage-indicative layer. The protection is essentially limited to the peripheral region of the wheel and does not extend to the central hub region.
Problems of existing wheel concepts made out of fiber reinforced materials are abrasion and other damage, contact corrosion, structural damage due to micro movement especially between the fixing bolts and the fibers.
Furthermore, in many cases the detection and assessment of damage in wheels made out of fiber reinforced material turns out to be difficult—if not even impossible—for the end-user. A main reason that external forces, such as impacting stones, can cause damage in underlying material while the material visible from outside stay intact. Therefore systems to indicate or highlight potential structural damage in a wheel made out of a fiber reinforced plastic are needed.
As well, for many methods used for the production of parts out of fiber reinforced materials, the tooling costs are relatively high. Hence, variations in the design of a wheel made out of such a composite material are in general relatively expensive if compared to e.g. wheels made out of conventional light metal alloys. Thus, methods are sought which allow inexpensive variations in wheel design.
Another problem which is common especially to relatively expensive types of wheels is that they are often prone counterfeiting and theft. Means to verify the authenticity of an original wheel as well as to identify a previously stolen wheel therefore are important for customer safety, as well as for crime prevention and law enforcement.